In connection with the design of a personal computer to be added to the commercially available family of IBM PS/2 personal computers, a requirement or objective existed to detect the number of single, in-line memory modules (SIMMs) installed in the computer when the computer is restarted. The number of installed modules would be either in a first range up to six SIMMs, or in a second range up to sixteen SIMMs. Certain models of the PS/2 personal computers, such as the Models 90 and 95, have memories made up of a number of SIMMs. Each SIMM includes, in addition to the normal random access memory, a register for storing presence detect bits indicating the size and speed of the SIMM. The SIMMs are designed to be plugged into sockets that are driven so that if a socket is empty, a predetermined pattern of presence detect bits, (e.g.,all ones) is provided to indicate the socket is empty. The presence detect information is treated as programmable option select (POS) information that is gathered along with other POS information during a power on self test (POST) and is used to test and verify the configuration of the computer each time the computer is started.